The present invention relates to a diamond blade for an apparatus such as a cutting saw machine for grinding or cutting workpieces such as brick, concrete, granite, marble, etc., and more particularly to a diamond blade having a rim type cutting tip in which at least two diamond layers are longitudinally disposed along the rotation direction of the diamond blade to form microscopic linear cutting grooves to cause portions of the workpieces between the cutting grooves to be crushed in chips of relatively large size by non-diamond portion of the rim type cutting tip during the cutting operation, and thereby to enhance cutting rate of the diamond blade and to prevent the crushed chips from dispersing easily in the air and from causing bad affects to user's health and the contamination of environment.
FIG. 1 is a front view of one conventional diamond blade for a cutting saw machine for grinding or cutting workpieces in which diamond particles are randomly distributed on a rim type cutting tip thereof, the conventional diamond blade 1 comprises a steel wheel body 2 whose center hole is connected with a shaft of electric motor, and a rim type cutting tip 3 disposed circumferentially and fixedly on the steel wheel body 2. Here, the rim type cutting tip 3 is fabricated by mixing abrasive materials such as diamond and metal powders composing of cobalt, nickel, bronze, copper, etc., or particles of resin or ceramic, and then forming a rim of predetermined shape from the mixed particles.
Especially, the diamond particles 4 are randomly distributed in the inside and on the surfaces of the rim type cutting tip 3 as shown in FIG. 3. 
In the diamond blade 1, as shown in FIG. 3, both outer surfaces of the rim type cutting tip 3 contacts with corresponding surface portion of workpiece 18, and grinds it to form a cutting slot 16 in workpiece 18 during the cutting operation.
Minute chips produced during the cutting operation of the rim type cutting tip 3 are gathered in the cutting slot 16 and then discharged from there outside by the rotation of the rim type cutting tip 3.
However, since both surfaces of the rim type cutting tip 3 of the diamond blade 1 has the same shape and the same material composition on the whole, both edges 15 of the rim type cutting tip 3 contacting with the side walls and bottom of the cutting slot 16 are defaced faster than the center 17 of the rim type cutting tip 3 contacting only with the bottom of the cutting slot 16.
Accordingly, the contacting area between the upper surface of the rim type cutting tip 3 and the workpiece 18 is enlarged to increase resistance of the workpieces 18, and thereby causing poor cutting and decreasing cutting rate and the life of the diamond blade 1.
Further, since the size of chips produced during the cutting operation is are relatively very minute, these chips remains in the cutting slot 16 and prevents the upper surface of the rim type cutting tip 3 from grinding the bottom of the cutting slot 16, and thereby decreasing cutting rate. Also, if those minute chips discharged from the cutting slot 16 are dispersed in the air, it causes the bad affects to user's health and the contamination of environment.
To improve these problems, there has been proposed a diamond blade 11, as shown in FIG. 2.
FIG. 2 is a front view of the other conventional diamond blade in which diamond particles are randomly distributed in rim type cutting tip thereof and a plurality of depressed portions are disposed in both outer surfaces of the rim type cutting tip thereof. Namely, the conventional diamond blade 11 has a plurality of depressed portions 19 formed with a  predetermined interval in both surfaces of a rim type cutting tip 13. Here, the rim type cutting tip 13 is disposed circumferentially and fixedly on a steel wheel body 12 and has a plurality of diamond particles 14 on its surfaces.
However, even though the diamond blade 11 is improved tip to be defaced during the cutting operation as the minute chips are effectively discharged from the cutting slot, it has still the disadvantages to deface both edges of upper surface to induce poor cutting, to decrease its own cutting rate and life of blade, to produce very minute chips to decrease its own cutting rate, and to disperse the produced minute chips in the air, which cause the bad affects to user's health and the contamination of environment.